Possible reasons for high resistance during the use of bag filters

Possible reasons for high resistance during the use of bag filters

The resistance of a bag filter is determined by its design, but in the operation of the bag filter, if it is found that the resistance of the bag filter increases sharply in a short period of time, it means that there is a problem with the bag filter and it should be repaired and adjusted in a timely manner.

There are two reasons for excessive resistance:

1. The dust collector runs immediately after the system is in operation;

2. The bag filter works for a period of time;

If the newly installed dust collector is not designed properly, it can easily cause a phenomenon

The two are caused by operational issues and maintenance: the main reasons are poor cleaning of filter bags, clogged filter bags, and uneven distribution of air intake. The brief reasons are as follows:

(1) Poor adjustment of cleaning device:

Check the quality of compressed air for oil and water;

Check if the gas supply pipeline is unobstructed;

Check if the pulse solenoid valve is working properly, if the fastening bolts are loose, if the diaphragm is damaged, if the electromagnetic coil is loose, and if the valve core is stuck.

Whether the settings of the sequence controller meet the requirements and have undergone changes; Is the installation of spray branch pipes and Venturi pipes accurate.

(2) Filter bag blockage

The main reasons for filter bag blockage are excessive filtration speed, fine dust, sticky dust, poor cleaning of filter bags, and damage to filter bags. If the filtering gas speed of the dust collector exceeds the design standard of the filter bag, it is easy for small dust in the exhaust gas to get stuck in the fibers of the filter bag, causing the filter bag to clog on the surface of the filter bag. Using thin film filter materials or pre coating protective powder layer is a better method.

For high viscosity dust, it is necessary to reduce the filtering gas velocity, increase the pulse blowing pressure, or use offline pulse cleaning of the filter bag. However, a good method is to increase the filtering area to reduce the filtering speed and extend the service life of the filter bag. Poor dust removal of filter bags mainly includes frequent dust removal and long dust removal time. Excessive dust removal time can easily loosen the fiber structure of the filter bag, increasing the blockage of the filter bag by fine dust in the exhaust gas. If the dust removal time is too long, the initial dust on the surface of the filter bag will be removed together. If the cleaning time is too short and the dust on the surface of the filter bag is not completely removed, the filtration will start immediately, and the dust will gradually accumulate on the surface of the filter bag, leading to blockage of the filter bag. To solve this problem, adjustments can be made through several trial runs.

The reason for the dampness of the filter bag: the dust collector shell is not tightly sealed, leaking water, humid air enters, the compressed air used for back blowing dust cleaning is not clean (containing oil and water), and the compressed air used for dust cleaning is too cold. To prevent the filter bag from getting damp, compressed air used for dust cleaning can be added for insulation, cooling, oil removal, and water removal in cold regions. After the bag filter stops, continue cleaning the dust for 10-20 minutes. Moisture is a major cause of filter bag blockage. The reason for moisture content is usually condensation at low temperatures, especially when dealing with combustion or high-temperature flue gas. The following methods can be used to prevent this situation:

Avoid improper activation;

(3) Avoid starting the bag filter when there is high resistance;

Open below dew point:

After the dust collector stops, if there is condensation on the surface of the filter bag, it should be restarted. This will allow a large amount of dusty air to enter, and high humidity will cause the surface of the filter bag to become cloudy; To prevent this situation, the dusty air at the inlet of the dust collector should be preheated, or the dust layer should be pre coated.

Starting the machine below the dew point can easily cause problems when the bag filter operates below the dew point. If the intake distribution is uneven, it is easy to cause corrosion of the dust collector casing. Therefore, bag filters should be avoided from working below the dew point and insulation devices should be used.

Air infiltration often occurs in filter flanges, access doors, or moving devices of filters. If the seal is not tight, external air will enter the filter. During the treatment of high-temperature exhaust gas, a low-temperature zone will be generated inside the filter, leading to low-temperature condensation. Corrosion of the filter bag can cause it to become damp.

3. Improper gas distribution

If the inlet distribution of the bag filter is uneven, the resistance will be high when the bag filter is started, so the inlet distribution of the bag filter should be uniform.